Effects of Orthodontic & Orthopedic /fixed orthodontic courses by IDA

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Effects of Orthodontic & Orthopedic Treatment on TMJ : 

Effects of Orthodontic & Orthopedic Treatment on TMJ www.indiandentalacademy.com

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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com

Contents : 

Contents Introduction History Major reviews Physiology of TMJ Effect of some occlusal conditions Effect of orthopedic appliances -growth relativity -reviews of various orthopedic appliance effects www.indiandentalacademy.com

Introduction : 

Introduction DO NO HARM The harmony of the interface between the teeth ,muscles ,nerves, supporting tissue, and temporomandibular joint all must be in balance to provide health ,functional efficiency,esthetics and stability to entire stomatognathic system www.indiandentalacademy.com

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The methods and means of orthodontic treatment are a factor of the dentist education and personal preference based on experience,objectives and skills.the comparison of cephalometric records ,facial and dental photographs,as well as the alveolar –periodontal status are the usual means of clinical assessment. the functional component of occlusal interdigitation has entered the picture more emphatically in the past two decades www.indiandentalacademy.com

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Numerous suppositions ,hypotheses, and theories concerning the function and dysfunction of the TMJ and the total stomatognathic system have been given ,the recommendations have ranged from “do nothing” to “do everything” to prevent or correct dysfunction and to ensure proper maxillary/mandibular stability www.indiandentalacademy.com

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There continues to be a clash between the research community and certain clinicians regarding the relation between the functioning dentition and the temporomandibular joints www.indiandentalacademy.com

History : 

History Prentiss & Summa 1918-studied relation between loss of teeth and jaw dysfunction and reported pressure atrophy of meniscus Hildebrand recorded mandibular & condylar movements in frontal and sagittal plane & discussed the influence of various food types on different mandibular movements www.indiandentalacademy.com

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Costen 1934 ,described a group of symptoms associated with marked overbite or mandibular overclosure “Costen’s Syndrome” Shultz 1947, presented a theory that lax ligaments could result in subluxation followed by complete luxation www.indiandentalacademy.com

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In late 1940s through 1960s ,a neuromuscular component of normal and abnormal jaw function began to appear Schwartz presented the theory that pain associated with mandibular dysfunction perhaps had its origin in musculature.pain could be caused by muscle spasm www.indiandentalacademy.com

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Bonica was among the first to describe the etiology and treatment of myofascial pain syndrome ,he also described hypersensitive trigger areas Later Schwartz concluded that predisposition ,psychologic as well as physiologic is more important than the particular form of the precipitating factor itself www.indiandentalacademy.com

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Moulton reported that significant and complicating emotional factors can be strong differential diagnosis for facial pain Laskin 1969,questioned the role of occlusion in creating symptoms with the exception of frank iatrogenic factors .his studies supported the idea that muscle fatigue was the prime cause of pain www.indiandentalacademy.com

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Brodie stressed the importance and relation of the temporomandibular joints to orthodontic therapy Thompson ,one of brodie’s student studied the clinical importance of the temporomandibular joints to the orthodontic specialty www.indiandentalacademy.com

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Brodie ,Thompson &Ricketts were the leaders in the American orthodontic community in emphasizing the interrelation of occlusion to the TMJ www.indiandentalacademy.com

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Does a malocclusion contribute to or cause TMD ? Different groups exist –for it and against it And some are of the view that certain orthodontic procedures could produce TMD symptoms Some authors concluded as the relationship of the TMDs to occlusion and orthodontic treatment is minor www.indiandentalacademy.com

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What majority concluded ? Probable explanation . Some important correlations. www.indiandentalacademy.com

Some questions to be answered : 

Some questions to be answered Does orthodontic treatment lead to a greater incidence of TMD? Does type of appliance make a difference? Does the extraction as part of orthodontic protocol lead to greater incidence of TMD? Can orthodontic treatment lead to a posterior displacement of the condyle? Does orthodontic treatment prevent TMD? www.indiandentalacademy.com

Effect of orthodontic treatment on TMJ : 

Effect of orthodontic treatment on TMJ Studies from mid 1960s onwards Two studies were done as part of a National Institutes of Dental Research (NIDR) research contract on the long-term effects of orthodontic treatment. Sadowsky and BeGole reported on the findings from 75 adult subjects who were treated with full fixed appliances as adolescents approximately 20 years previously and compared them with a similar group of 75 adults with untreated malocclusions. www.indiandentalacademy.com

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Another independent study, also part of the NIDR research contract, performed at the Eastman Dental Center on 111 subjects who received orthodontic treatment a minimum of 10 years previously and were compared with 111 adults with untreated malocclusions. Nonextraction and extraction cases were well represented in both the above studies. www.indiandentalacademy.com

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Findings were prevalence of symptoms varying between 15% to 21% and 29% to 42% for signs ( joint sounds), there was no statistically significant difference between treated and untreated subjects in either of the studies. The conclusion from the above two studies was that orthodontic treatment performed during adolescence did not generally increase or decrease the risk of developing TMD in later life. www.indiandentalacademy.com

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Larsson and Ronnerman studied 23 Swedish adolescent patients who were treated orthodontically 10 years previously, 18 of whom had fixed appliances and 5 of whom had a functional appliance (activator). In 31% of the subjects mild dysfunction was recorded clinically and only one subject (4%) had severe dysfunction recording . In comparing their results with other published epidemiologic studies, they concluded that extensive orthodontic treatment can be performed without fear of creating complications of TM dysfunction. www.indiandentalacademy.com

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Janson and Hasund in Norway studied 60 patients with Class II, Division 1 malocclusions who were treated as adolescents an average of 5 years out of retention, 30 of whom were treated with a four premolar extraction strategy; the 30 nonextraction patients received a combination of headgear and activator initially, followed by fixed appliances. A sample of 30 untreated patients were used as a control. www.indiandentalacademy.com

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. Anamnestic symptoms were found in 42% of subjects overall (treated and untreated), with similar findings for the clinical dysfunction index, which were mostly of a mild-to-moderate degree. The findings supported the conclusion that there was not a significant risk of developing TM dysfunction when treating orthodontic patients with relatively severe malocclusions www.indiandentalacademy.com

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Lieberman et al in a survey of 369 Israeli school children 10 to 18 years of age,. found no association between previous orthodontic treatment and increased symptoms of mandibular dysfunction www.indiandentalacademy.com

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In a prospective longitudinal study, Dibbets and van der Weele in the Netherlands studied 63 orthodontic patients who were treated with a modified functional activator and 72 patients who were treated with fixed appliances (Begg technique) mostly with an extraction treatment strategy during childhood and adolescence. The patients were followed over a 10-year period. A subsample of patients at the pretreatment stage served as an internal control group. www.indiandentalacademy.com

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Objective signs increased from 21% to 41% overall; however, the authors attributed the increase to age rather than orthodontic treatment on the basis of an internal control group . The findings for subjective symptoms, objective signs and radiographic changes in the condyles supported the conclusion that orthodontic treatment does not induce TM dysfunction. the fixed appliance group as compared with the functional appliance group had higher percentages of objective symptoms after retention, no differences existed at the 10-year follow-up. www.indiandentalacademy.com

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Dahl et al. conducted a retrospective study of 51 Norwegian subjects who were 19 years of age and an average of 5 years after orthodontic treatment. Signs and symptoms of craniomandibular disorders (CMD) were compared with 47 untreated 19-year-old persons. The clinical dysfunction index showed mild symptoms in 43% and moderate symptoms in 28% of the treated group and 40% and 13% in the untreated group. They concluded that there were no substantial differences between these two groups. www.indiandentalacademy.com

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Smith and Freer in Australia examined 87 patients who received full fixed appliances during adolescence, approximately two-thirds involving extractions, and who were an average of 52 months(4.5 years) after retention and compared them with an untreated control group of 28 subjects. Symptoms were found in 21% of the treated subjects and 14% of the controls, which was not statistically significant . Their results rejected the hypothesis of a significant association between orthodontic treatment and occlusal or TMJ dysfunction. www.indiandentalacademy.com

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In a report of a survey of 568 dental students ages 20 to 43 years at the Medical College of Georgia, Loft et al. found a significant association between facial discomfort and pain as reported by the female subjects only, who had received orthodontic treatment. www.indiandentalacademy.com

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Nielsen et al. evaluated 706 Danish children of whom 295 (37%) had completed orthodontic treatment and were between 14 and 16 years of age. The 388 untreated subjects served as controls. Approximately one-third of the subjects had signs of TM dysfunction. It was found that the functional status was not related to the type of orthodontic treatment or the use of removable or fixed appliances, including extraction therapy. www.indiandentalacademy.com

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According to Thompson faulty intercuspation of the teeth and dental intrusions into the freeway space are two of the many etiologic factors that may lead to joint dysfunction and its sequelae. Dysfunction of the joints and musculature may occur before orthodontic treatment, during treatment, or anytime after treatment has been completed. Whether related directly to treatment or not, the orthodontist must be alert to recognize such dysfunction and intervene whenever it may occur. www.indiandentalacademy.com

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If the condyles are not growing upward and backward at the time of orthodontic tooth movement, the body of the mandible will not be projected downward and forward with the rest of the face, and the normal dental freeway space can be lost. The result is downward and backward rotation of the mandible, which may cause clicking and other symptoms in the joint. www.indiandentalacademy.com

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Additional condyle growth after other facial growth has stopped is a special concern because it can alter the occlusion and joint function. There may be no joint clicking or other symptoms at 12 or 14 years of age, yet pronounced symptoms 5 years later. www.indiandentalacademy.com

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in a dental malocclusion with shortened arch length and insufficient space for canine eruption, the incisors may be intruding into the freeway space. The resultant incisal interference can cause posterior displacement of the mandible with possible clicking of the joints. bilaterally narrow maxillary dental arch, as may be caused by thumb or finger sucking can cause the mandible to be displaced into a crossbite relation, often combined with a Class II molar relation on the side of the crossbite. In this situation, clicking is often found in the joint on the side of the crossbite www.indiandentalacademy.com

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A prospective longitudinal study of 238 subjects in three different age groups (7, 11, and 15 years) was conducted over a 4 to 5-year period by Egermark-Eriksson et al. in Sweden. Corrective orthodontic treatment had been done on 35 subjects. Approximately 20% of subjects in the older age group had clinical signs of CMD. No differences were found in the prevalence of signs or symptoms of CMD between orthodontically treated and untreated subjects. www.indiandentalacademy.com

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Dibbets and van der Weele reported the findings from their prospective longitudinal study in the Netherlands over a 15-year period for 111 of the original 172 orthodontically treated patients of the average age of 12.5 years who were enrolled in the study. Removable appliances (functional) were used in 39%, fixed appliances (Begg) in 44%, and chin cups in 17% of cases. A nonextraction approach was used in 34% of cases, four premolars were extracted in 29%, and other extractions in 37%. www.indiandentalacademy.com

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They evaluated subjectively perceived symptoms, which increased from 20% to 62%; objectively identified clicking/crepitation, which increased from 23% to 36% after 4 years and then stabilized; and the radiographic appearance of the condyle, which increased slightly during the first 4 years and then stabilized at around 25%. It was found that during the first years of the study, age probably accounted for the statistical differences in percentages between the three types of treatment; www.indiandentalacademy.com

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the influence of age disappeared after 10 years. For the first 10 years there was no difference between the three treatment groups with regard to subjective clicking., after 15 years it was greater for the four premolar extraction group Objective clicking was always more frequent in the four-premolar extraction group at all time points, Clicking frequency, subjective or objective, was always higher in the four premolar extraction group even before treatment was started. www.indiandentalacademy.com

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They concluded that the original growth pattern, rather than an extraction treatment strategy, was the most likely factor responsible for the frequency of CMD reported many years posttreatment. www.indiandentalacademy.com

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Sadowsky et al. reported on their prospective longitudinal study of 160 patients of average age of 14 years 6 months (range 9 to 41 years), treated with full fixed appliances for an average of 35 months (range 14 to 53 months). Of the 160 patients, 54% were treated with an extraction treatment strategy and 42.5% were treated with nonextraction (3.1% had missing data). In addition to recording symptoms, joint sounds were objectively recorded with an audiovisual videotape system. www.indiandentalacademy.com

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Before treatment 25% of patients had joint sounds, whereas 16.2% had sounds after treatment. In 27 patients the sounds were not evident after treatment, in 13 patients there was no change in occurrence, and sounds developed in 13 patients by the end of treatment. The findings did not indicate a progression of signs/symptoms to more serious problems. The conclusions were that orthodontic treatment did not pose an increased risk for the development of TM joint sounds irrespective of whether extraction or nonextraction treatment strategies were used. www.indiandentalacademy.com

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Lotika Wadhwa,, Ashok Utreja,, and Amrit Tewari, compared the status of signs and symptoms of TM disorders in three groups of adolescents and young adults. The groups consisted of 30 persons with normal occlusions, 41 with untreated malocclusions, and 31 with treated malocclusions. The clinical status and subjective symptoms of TM dysfunction were recorded The results showed that the normal occlusion group had the maximum number of persons free from any dysfunction, www.indiandentalacademy.com

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but the differences between the groups in the distribution of persons according to the anamnestic and clinical dysfunction indices were not significant. The only statistically significant finding was the difference in the clinical dysfunction index scores of the persons with normal occlusions and untreated malocclusions. According to anamnesis, the most frequently reported symptoms were related to periods of stress. www.indiandentalacademy.com

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Among the clinical signs and symptoms, the most commonly occurring were crepitations on palpation and sounds on auscultation of the joints in all the three groups. In conclusion, the absence of substantial differences between the three groups indicates that the role of orthodontic treatment in either precipitation or prevention of TM dysfunction is questionable. www.indiandentalacademy.com

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O'Reilly,. Rinchuse, Close, studied effect of classII elastic and extraction on TMJ The experimental group comprised 60 subjects, 30 girls and 30 boys, with a mean age at the start of treatment of 15.3 years (range 14.3 to 16.1 years). These subjects received orthodontic treatment with edgewise straight wire appliances, extractions, and retraction of the anterior maxillary teeth with Class II elastics from canines to mandibular second molars. The teeth extracted were the maxillary first premolars in 48 patients and the maxillary and mandibular first premolars in 12 subjects. www.indiandentalacademy.com

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The control group consisted of 60 orthodontically untreated subjects. The only significant finding in this study was pain (mild) on palpation "lateral to the TMJ capsule" at the 8- to 10-month period during orthodontic treatment; this was present for 40% of the orthodontically treated subjects. There is no logical explanation for this finding. this study demonstrated that edgewise straight wire orthodontic treatment involving extractions and Class II elastics have no effect, or little effect (i.e., mild pain "lateral to TMJ capsule"), on TMJ signs and symptoms. www.indiandentalacademy.com


CONDYLAR POSITION AND ORTHODONTIC TREATMENT Orthodontic treatment, particularly involving premolar extractions, has also been implicated in producing a posteriorly positioned condyle. It has been reported anecdotally that an internal derangement may therefore result. In a cross-sectional study, Gianelly et al. evaluated condylar position with corrected tomograms before orthodontic treatment in 37 consecutive patients ages 10 to 18 years and compared them with 30 consecutively treated four premolar extraction cases at the completion of treatment. www.indiandentalacademy.com

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All patients were treated with fixed appliances, 23 with the edgewise technique and 7 with the Begg technique. They could find no difference in condylar positions between the extraction and the untreated groups. It was concluded that extraction therapy did not appear to be an iatrogenic cause of distally positioned condyles. Condylar position tended to be centered on average; a wide variation in position was noted. Similar wide variations in normal condylar position has been reported by several authors as discussed by Tallents et al. www.indiandentalacademy.com

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William E. Wyatt,reported In Class ll malocclusions with deep interlocking cusps headgear and/or Class 11 elastics are often used in an effort to get the patient into a Class I cuspal relationship. As the maxilla is moved backward, the muscles of mastication will attempt to retract the mandible when the patient closes in to maximum intercuspation. This compensating movement by the mandible can put distal pressure on the condyles and conceivably cause an anterior dislocation of the disk www.indiandentalacademy.com

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. Midsagittal section through TMJ. 1, Superior joint space. 2, Cortical plate of eminence. 3, Superior articulating surface of disk. 4, Articular surface of eminence. 5, Avascular portion of disk. 6, Articular surface of condyle. 7, Inferior joint space. 8, Cortical plate of condyle. 9, Fibers of superior head of lateral pterygoid muscle. 10, Fibers of inferior head of lateral pterygoid muscle. 11, Bilaminar zone of disk. 12, Elastin fibers attaching disk to rear wall of fossa (in posterior attachment). 13, Inelastic distal ligament. 14, Vascular complex (retrodiskal tissue). 15, Auditory canal. 16, Attachment of distal ligament to condyle. www.indiandentalacademy.com

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Midline switch or cross elastics have a more subtle effect. As the jaw is pulled to one side, distal pressure is put on one condyle only. If this creates a TMJ problem, midline elastics should be worn only during waking hours so that muscles can help to hold the mandible forward Lower headgears or reverse headgears that exert distal pressure on the chin and Class lll elastics are a very important part of orthodontic treatment, but they too can put distal pressure on the mandible.. www.indiandentalacademy.com

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If there is a developing problem, it is better to have the patient wear lower or reverse headgear and Class III elastics only during waking hours. During this period lower or reverse headgears have little effect on the TMJ because muscle tone (tension) positions the mandible forward. www.indiandentalacademy.com

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R S Nanda & Carlton 2002 conducted a follow-up prospective longitudinal study to determine what changes occurred in the condyle/fossa relationship after treatment. Orthodontic posttreatment records, including corrected tomograms of 106 white patients (58 Class I and 48 Class II Division 1), from a pretreatment sample of 232 patients, were analyzed. The average pretreatment age was 13.6+ 3.0 years. The average length of treatment was 2.3 years for the Class I group and 2.8 years for the Class II Division 1 group. www.indiandentalacademy.com

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With orthodontic treatment, the condyle became more concentrically positioned, There was no statistically significant correlation between changes in the condyle/fossa relationship based on age, gender, skeletal or dental variables, signs or symptoms of temporomandibular disorder, headgear use, type of elastics, or nonextraction vs extraction treatment. www.indiandentalacademy.com


TMJ SOUNDS AND ORTHODONTIC TREATMENT Temporomandibular joint sounds are a common finding and occur in approximately 20% to 30% of the population including patients before orthodontic treatment. Wabeke et al. on TMJ clicking in 1989- joint sounds are the most frequent sign of TMD and are often present in the absence of symptoms. Treatment to eliminate joint sounds is usually unsuccessful. In the absence of pain or significant discomfort, patients with joint sounds should be reassured and monitored over time. www.indiandentalacademy.com

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Approximately half of the patients with joint sounds have a reciprocal click, which is often associated with disk displacement with reduction. In many patients the reciprocal clicking may be explained by condylar dislocation anterior to the disk or the articular eminence. Joint sounds or other symptoms may change in character or disappear over time and do not usually progress to joint degeneration. www.indiandentalacademy.com


PROGRESSION OF SIGNS/SYMPTOMS OF TMD Wanman and Agerberg studied 258 subjects from 17 to 19 years of age and found no change in symptoms in 60%, whereas 20% improved, and 20% got worse. In a study of 70 patients with reciprocal clicking whose mean age was 30 years (range 10 to 69 years) Lundh et al. found that over 3 years 71% showed no change, 29% decreased, and 9% progressed to locking. www.indiandentalacademy.com

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Magnusson et al., in following 119 subjects longitudinally from age 15 to 20 years, found no change in clinical signs in almost half the subjects, with almost equal rates of improvement and impairment. www.indiandentalacademy.com

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clicking is generally benign and does not progress to more serious clinical dysfunction or disease, even in subjects who previously had symptoms., subjects with symptomatic clicking can be successfully treated without addressing the position of the disc joint sounds alone are not pathognomonic of disease and may be present for up to 10 years without progression. joint sounds do not necessarily indicate a "problem" but may represent a "risk" factor; however, no treatment should be considered in the absence of symptoms. www.indiandentalacademy.com

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If painful symptoms arise during orthodontics, therapy may have to be modified, gross occlusal interferences relieved, and forces tending to distalize the mandible eliminated www.indiandentalacademy.com

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Niler &Kulor studied the occlusal changes in girl subjects with classII malocclusion undergoing treatment and compared with normal subjects Orthodontic treatment did not increase the risk for or worsen pretreatment signs of TMD in a 2 years perspective Class II Patients with TMD symptoms before treatment benefited from treatment The normal group had lower prevalence of signs of TMD as compared to orthodontic and untreated classII groups www.indiandentalacademy.com

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Inger Egermark, Magnusson,. Carlsson, 20-Year Follow-up of Signs and Symptoms of Temporomandibular Disorders and Malocclusions in Subjects With and Without Orthodontic Treatment in Childhood 402 randomly selected 7-, 11-, and 15-year-old subjects were examined clinically and by means of a questionnaire for signs and symptoms of TMDs. The examination was repeated after five and ten years. After 20 years, 320 subjects (85% of the traced subjects) completed the questionnaire. www.indiandentalacademy.com

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The oldest age group, 35 years of age, was invited to a clinical examination, and 100 subjects were examined. The correlations between signs and symptoms of TMD and different malocclusions were mainly weak,. Lateral forced bite and unilateral crossbite were correlated with TMD signs and symptoms at the 10- and 20-year follow-ups. Subjects with malocclusion over a long period of time tended to report more symptoms of TMD and to show a higher dysfunction index, compared with subjects with no malocclusion at all. www.indiandentalacademy.com

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There were no statistically significant differences in the prevalence of TMD signs and symptoms between subjects with or without previous experience of orthodontic treatment. This 20-year follow-up supports the opinion that no single occlusal factor is of major importance for the development of TMD,. subjects with a history of orthodontic treatment do not run a higher risk of developing TMD later in life, compared with subjects with no such experience. www.indiandentalacademy.com

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Mohlin, Derweduwen, Pilley, Kenealy, examined total of 1018 subjects at the age of 11 years, 791 were reexamined at 15 years, 456 at 19 years, and 337 at 30 years. Anamnestic and clinical recordings of temporomandibular disorder (TMD) were made. Morphology, including calculation of peer assessment rating (PAR) scores, was recorded. Previous history of orthodontic treatment was assessed. The subjects completed four measures. The malocclusion prevalence, occlusal contacts, psychological factors, and muscular endurance in subjects with no recorded signs and symptoms of TMD were compared with those with the most severe dysfunction at 19 years of age. www.indiandentalacademy.com

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The further development of TMD to 30 years of age was followed. PAR scores were significantly higher in the subjects with the most severe dysfunction. Apart from crowding of teeth, no other significant differences were found between the groups with regard to separate malocclusions, tooth contact pattern, orthodontic treatment, or extractions. Significant associations between TMD and general health and psychological well-being as well as the personality dimension of neuroticism and self-esteem were found. www.indiandentalacademy.com

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During the period from 19 to 30 years, the prevalence of muscular signs and symptoms showed considerable reduction, whereas clicking showed a slight increase. Locking of the joint showed a decrease from 19 to 30 years. One-quarter of the TMD subjects showed complete recovery. Thus, orthodontic treatment seems to be neither a major preventive nor a significant cause of TMD. www.indiandentalacademy.com

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Probable Explanation www.indiandentalacademy.com

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TMJ = ginglymoid diarthrodial joint Ginglymoid =hinge movement Diarthrodial =discontinous articulation that permits greater freedom of movement It is a simple type of synovial joint www.indiandentalacademy.com

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Functional demands require extensive movement The articulating surfaces must be completely disconnected yet firmly held in place Therefore articulating surfaces are composed of tissue that is neither innervated nor vascularized www.indiandentalacademy.com

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In absence of vasculature ,nutritional and metabolic activities must be provided for by way of a special joint fluid that is supplied by vessels free from interarticular pressure Encapsulation is required to contain the joint fluid –synovial fluid www.indiandentalacademy.com

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The disconnected bones of synovial joint are supported by system of ligamentous structures that passively limit the amount of separation permitted by the articular surfaces and that restrain the degree and direction of joint movement a system of skeletal muscles that actively hold the parts in sharp contact during all functional activities and that furnish power for working movements www.indiandentalacademy.com

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Encapsulation –fibrous capsule is attached near the periphery of the articular surface Capsule is well vascularized and innervated The vessels supply tissue fluid which has free metabolic interchange with the synovial fluid within joint cavity Synovial membrane that secretes the fluid lines the inner surface of fibrous capsule www.indiandentalacademy.com

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It also serves as a joint lubricant and shock absorber Capsule is innervated with nociceptors with a high threshold, so that pain is usually not felt unless the strain ,distortion, or distension is considerable www.indiandentalacademy.com

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Articular surfaces Noninnervated ,nonvascularized articular tissue in most synovial joints is hyaline cartilage ,but in TMJ it is slightly different from hyaline cartilage ,it is more of fibrous nature www.indiandentalacademy.com

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Retrodiscal tissue Highly vascularized tissue it is the main source of synovial fluid to both compartments of the TMJ Any damage at retrodiscal tissue will be manifested at articular surface of the joint www.indiandentalacademy.com

Weeping lubrication : 

Weeping lubrication Described by DuBrul Under all non compressive situations the articular tissue takes up synovial fluid Under compressive force ,this fluid is expelled onto the surface in tiny droplets and forms a layer of liquid that acts as a lubricating film Articulating surfaces may be moved under pressure without sustaining damage www.indiandentalacademy.com

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This effect makes extensive joint movement ,even under considerable pressure harmless to the joint But when all the fluid is expelled out ,further movement is without adequate lubrication ,and resultant friction is potentially damaging to the articular surfaces www.indiandentalacademy.com

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3 factors are important Length of time Degree of pressure Extent of movement www.indiandentalacademy.com

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Momentary high pressure even with extensive movement is harmless as well as limited sustained pressure without movement www.indiandentalacademy.com

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Boundary lubrication it pertains to the reservoir of synovial fluid in the joint cavity which lubricates the articular tissues by surface contact and is the means of replenishing that which enters into the weeping lubricating mechanism When synovial fluid becomes too viscid its lubricating qualities are seriously impaired –Gelation www.indiandentalacademy.com

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Interarticular pressure {passive & active} Passive It provides continuous sharp contact of the articulating surfaces in the resting joint and during unstressed movements.It results from muscle tonus as affected by gravitational force which varies with posture. It also varies with emotional stress ,tension ,activities ,fatigue,time of day,age and illness www.indiandentalacademy.com

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Active It results from the contraction of skeletal muscles as required to overcome resistance and accomplish the intended task –the stresses and forces of musculoskeletal activity It is extremely variable www.indiandentalacademy.com

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Loading It refers to the effect of active interarticular pressure on the joint surfaces due to muscle action as affected by resistance Proteoglycans found in the collagen matrix of superficial layers of articular tissue is a measure of resilience of that tissue and is indicative of location and degree of loading www.indiandentalacademy.com

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Overloading static dynamic www.indiandentalacademy.com

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Remodeling –if overloading occurs at a tolerable rate Degeneration –if the requirement for change exceeds the capability of the articular surface to remodel ,degenerative changes may occur www.indiandentalacademy.com

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overloading in occluded position has the potential to exceed the protective effect of weeping lubrication and may predispose to damage (bruxism) Occlusal conditions (normal or abnormal ) that operate prior to intercuspation of the teeth are not damaging to articular structures,because the do not violate the limits of weeping lubrication www.indiandentalacademy.com

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Important question that still remains is how this minor contribution can be identified within the population of TMD patients The key word is to reach to an accurate diagnosis before any treatment is begun Then only a treatment regime should begin to deal with each specific signs and symptoms www.indiandentalacademy.com

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For orthodontic patients all the pretreatment records and documenting ranges of motion ,muscle tenderness,evidence of joint sounds, locking or irregular movements and patients subjective location of percieved pain are to be recorded Always avoid promising the patient that you will relieve the signs and symptoms with treatment www.indiandentalacademy.com

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Precipitating factors of TMD symptoms can be dental procedures including orthodontic extra and intra-oral appliances as well as mechanics which result in inadvertent and rapid occlusal table alteration www.indiandentalacademy.com

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the benefits of orthodontic treatment in the management of temporomandibular disorders (TMD) is questionable, since the occlusion is considered as having a limited role in the cause of TMD as recently stated by Seligman and Pullinger. www.indiandentalacademy.com

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Pullinger and associates applied multiple factor analysis which indicated the low relation of occlusion to TMD ,some of the factors having a slight relationship are Apertognathia Overjet more than 6-7mm CR-CO discrepancy more than 4mm Unilateral lingual crossbite Five or more missing posterior teeth www.indiandentalacademy.com

Slide 95: 

Anterior open bite –predominantly associated with osteoarthrosis and myalgia For an anterior open bite to be etiological factor in for arthrosis ,some evidence of preceding derangement should be present that will lead to arthrosis It is hypothesized that the tendency to develop anterior open bite in osteoarthrosis is a consequence of and secondary to condylar osseous changes instead of etiology www.indiandentalacademy.com

Slide 96: 

TMJ condylar changes should be ruled out in any adult patient presenting with anterior open bite or rapid bite changes www.indiandentalacademy.com

Slide 97: 

Overjet –overjet more than 5 mm is associated with myalgia and arthrosis It is also considered a effect rather than etiology www.indiandentalacademy.com

Slide 98: 

Unilateral posterior maxillary lingual crossbite Considered as most common type of crossbite Individuals have a greater risk of internal derangement of the TMJ www.indiandentalacademy.com

Slide 99: 

Functional unilateral crossbite in childhood produces a displacement of the mandible resulting in right to left side differences in condyle fossa position at intercuspal position This leads to functional adaptation in the TMJ ,but in some individuals it is less than optimal and might be accomplished at the expense of the articular disc by development of internal derangement www.indiandentalacademy.com

Slide 100: 

Skeletal crossbite in adults does not appear to provoke TMJ symptomatology or disease www.indiandentalacademy.com

Slide 101: 

Posterior tooth loss There is a increased likelihood of patients with posterior tooth loss belonging to disease group (disc displacement and arthrosis ) A minimum of 5 posterior teeth need to be missing for correlation www.indiandentalacademy.com

Slide 102: 

Missing 2 or 4 premolars for orthodontic treatment had minimum contribution that is negligible www.indiandentalacademy.com

Slide 103: 

CR-CO discrepancy –discrepancy of about 1mm is almost seen in all groups Slides more than 2mm may accompany intracapsular problems For more serious derangments to occur a slide of 5mm may have to be present www.indiandentalacademy.com

Slide 104: 

Studies fail to demonstrate any association between occlusal interferences and TMD signs or symptoms Because contribution of occlusal slides is minor ,prophylactic elimination of slides through coronoplasty is difficult to support Even in the presence of symptoms removal of larger slides could be ill-advised until diagnosis is clarified ,because the slide may be consequence of TMJ articular disorder www.indiandentalacademy.com

Slide 105: 

Although contribution of occlusal features is not zero ,the importance should not be overstated ,since this may lead to neglect of many other causes of orofacial pain and dysfunction in a biologically multifactorial system www.indiandentalacademy.com

Effect of orthopedic treatment : 

Effect of orthopedic treatment Mandibular advancement appliances - Herbst,twin block,frankel etc Headgears Chincup www.indiandentalacademy.com

Slide 107: 

It was previously thought that increased activity in the postural masticatory muscles was the key to promoting condyle-glenoid fossa growth. 3 conditions that often overlap: normal condyle-glenoid fossa (CGF) growth, orthopedic remodeling as a result of condylar advancement, pathosis at the condyle. www.indiandentalacademy.com

Slide 108: 

Pathologic adaptations , show the C-GF region’s ability to be modified significantly. This type of growth is distinctly different from the limited short term growth modification observed with orthopedic displacement therapy. www.indiandentalacademy.com


HOW CONDYLAR MODIFICATIONS OCCUR the genetic theory, suggests the condyle is under strong genetic control like an epiphysis that causes the entire mandible to grow downward and forward. this may be related more to development of the prenatal than postnatal condyle, the theory does indirectly question the effectiveness of orthopedic appliances in condylar growth www.indiandentalacademy.com

Slide 110: 

long-term investigations actually showed clinically insignificant condylar growth modification after continuous mandibular advancement with a reasonable retention period in human. general growth of the condyle appears relatively unalterable in long-term studies. www.indiandentalacademy.com


LATERAL PTERYGOIDHYPERACTIVITY HYPOTHESIS The LPM hyperactivity theory brought forward by Charlier et al, Petrovic, and later McNamara, It suggests that hyperactivity of the lateral pterygoid muscles (LPM) promotes condylar growth. . Attachments of the LPM to the condylar head or articular disk may be expected to cause condylar growth, www.indiandentalacademy.com

Slide 112: 

Anatomic research has not found evidence that significant attachments actually exist The LPM tendon is observed attaching, to the anterior border of the fibrous capsule that attaches to the fibrocartilage of the condylar head and neck anteriorly Recently , permanently implanted longitudinal muscle monitoring techniques have found that the condylar growth is actually related to decreased postural and functional LPM activity. www.indiandentalacademy.com

The functional matrix theory, : 

The functional matrix theory, The principal control of bone growth is not the bone itself, but rather the growth of soft tissues directly associated with it. this was supported in part by investigations testing the different growth and developmental responses between the condyle and epiphysis, there has been no explanation as to exactly how condylar growth would be stimulated. Thus, this theory’s validity has been questioned. www.indiandentalacademy.com


GROWTH RELATIVITY HYPOTHESIS Growth relativity refers to growth that is relative to the displaced condyles from actively relocating fossae. Three Main Foundations The glenoid fossa promotes condylar growth with the use of orthopedic mandibular advancement therapy. displacement affects the fibrocartilaginous lining in the glenoid fossa to induce bone formation locally www.indiandentalacademy.com

Slide 115: 

This is followed by the stretch of nonmuscular viscoelastic tissues. Third is the new bone formation some distance from the actual retrodiskal tissue attachments in the fossa The glenoid fossa and the displaced condyle are both influenced by the articular disk, fibrous capsule, and synovium, which are contiguous, anatomically and functionally, with the viscoelastic tissues., condylar growth is affected by viscoelastic tissue forces via attachment of the fibrocartilage that blankets the head of the condyle www.indiandentalacademy.com

Slide 116: 

viscoelasticity addresses the viscosity and flow of the synovial fluids, the elasticity of the retrodiskal tissues, the fibrous capsule and other nonmuscular tissues including LPM perimysium, TMJ tendons and ligaments,other soft tissues, and bodily fluids. www.indiandentalacademy.com

Slide 117: 

Microscopic examination of TMJ- revealed direct connective tissue attachments of the retrodiskal tissues into the unique fibrocartilaginous layer of the condylar head . This fibrocartilage that caps the condyle in 3-dimensions is not found on epiphyses. www.indiandentalacademy.com

Slide 118: 


Slide 119: 

During orthopedic mandibular advancement, there is an influx of nutrients and other biodynamic factors into the region through the engorged blood vessels of the stretched retrodiskal tissues that feed into the fibrocartilage of the condyle. This gives rise to metabolic pump-like action of the retrodiskal tissues. www.indiandentalacademy.com

Slide 120: 

. This TMJ pump may initially act similar to a suction cup placed directly on the displaced condylar head to activate growth. The negative pressures, initially below capillary perfusion pressures, permit the greater flow of blood into the C-GF region This increases the flow to the synovial capillaries near the condyle and the fossa. www.indiandentalacademy.com

Slide 121: 

The concept suggests that -modification first occurs as a result of the action of anterior orthopedic displacement. Second, the condyle is affected by the posterior viscoelastic tissues anchored between the glenoid fossa and the condyle, inserting directly into the condylar fibrocartilage. Finally, it is hypothesized that displacement and viscoelasticity further stimulate (or turn on the light switch for) normal condylar growth by the transduction of forces over the fibrocartilage cap of the condylar head www.indiandentalacademy.com

Slide 122: 


Slide 123: 

The increase in new endochondral bone formation appears to radiate as multidirectional finger-like processes beneath the condylar fibrocartilage, and significant appositional(periosteal) bone formation is seen in the fossa www.indiandentalacademy.com

Growth restriction of glenoid fossa : 

Growth restriction of glenoid fossa Popovich and Thompson in healthy patients from the Burlington Growth Center, have found that the glenoid fossa grows in a posterior and inferior direction. the anterior slope of the articular eminence undergoes extensive resorption in a posterior and inferior direction and the posterior slope undergoes compensatory endosteal deposition until 7 years of age. www.indiandentalacademy.com

Slide 125: 

The condyles and fossae in individuals with average FMA grow generally in a posterior and inferior direction based on the cranial base superimposition. the fossa is reported to grow in the reverse direction, relocating anteroinferiorly to meet active condylar modification and to restore normal function during orthopedic treatment. This is a relative restriction of normal fossa growth, and it contributes toward Class II correction. www.indiandentalacademy.com

Epiphysis Versus Condyle : 

Epiphysis Versus Condyle the condyle appears to act like a light bulb on a dimmer switch. It lights up during advancement, dimming back down to near normal levels in retention. Its growth potential diminishes with age, whereas the glenoid fossa remodeling “lighting” potential lasts long into adulthood www.indiandentalacademy.com

Slide 127: 

Several investigations of relapse have said that C-GF growth modification cannot be maintained. . This does not prove, however, that growth of the condyle is strongly predetermined by genetic factors, like an epiphyseal growth center. The condyle can restore its relational position within individual limits. www.indiandentalacademy.com

Slide 128: 

The tissue-separating force of the epiphyseal growth center, is a main factor in determining length of long bones. epiphyseal cartilage has relatively little adaptive potential over the short-term and has no fibrocartilaginous cap. In contrast, the condyle does not have significant tissue-separating force and is dissimilar to the epiphysis functionally, anatomically immunologically, chemically, ontogenetically, or phylogenetically. Condylar cartilage is capable of both a degree of healthy intrinsic growth and significant adaptive growth with short-term mechanical stimulation. www.indiandentalacademy.com

Slide 129: 


Does Bite-Jumping Damage the TMJ? : 

Does Bite-Jumping Damage the TMJ? Due to the interference of the Herbst appliance with normal stomatognathic function, bite-jumping has been blamed of causing TMD. A report by Foucart et al in which 3 of 10 Herbst patients developed a disc displacement in 1 or both joints during treatment. www.indiandentalacademy.com

Slide 131: 

Pancherz evaluated the effects of the Herbst fixed functional appliance in the treatment of 22 growing patients with Class II, Division 1 malocclusions reported that the number of subjects with tenderness to palpation doubled during the initial 3 months of treatment. after appliance removal, most muscle symptoms disappeared and 12 months posttreatment the number of subjects with symptoms was the same as before treatment. www.indiandentalacademy.com

Slide 132: 

In a study done by Pancherz & Ruf on 62 consecutively treated Class II malocclusion it was found that A temporary capsulitis of the inferior stratum of the posterior attachment was induced during treatment. during the period from before treatment to 1 year after treatment, bite jumping with the Herbst appliance: (1) did not result in any muscular TMD www.indiandentalacademy.com

Slide 133: 

(2) reduced the prevalence of capsulitis and structural condylar bony changes, (3) did not induce disc displacement in subjects with a normal pretreatment disc position (4) resulted in a stable repositioning of the disc in subjects with a pretreatment partial disc displacement with reduction; (5) could not recapture the disc in subjects with a pretreatment total disc displacement with or without reduction .A pretreatment total disc displacement with or without reduction did not, however, seem to be a contraindication for Herbst treatment. www.indiandentalacademy.com

Slide 134: 

In another study long-term effects of the Herbst appliance on the temporomandibular joint were assessed in 20 patients (10 girls and 10 boys) who had completed treatment an average of 4 years previously. The TMJ analysis comprised of: The results revealed that the incidence of clinical signs and symptoms of temporomandibular disorders was within the range of “normal” reported in the literature. The frequency of disk displacement was not higher than in asymptomatic populations. www.indiandentalacademy.com

Slide 135: 

Major limitation of the study was that pretreatment status of TMJ condition was not known www.indiandentalacademy.com

Effect of Chin Cup Therapy : 

Effect of Chin Cup Therapy Posterior displacement of the condyle may be expected to occur with chin cup therapy that may displace the disc anteriorly ,but this has not been documented yet During active treatment TMJ pain is the most significant symptom This pain could be attributed to local muscle dysfunction due to deranged posterior occlusion www.indiandentalacademy.com

Slide 137: 

In the retention phase TMJ sounds are more common and pain reduced drastically If the chin cup therapy is 6 months or shorter the symptoms vanish faster as compared to longer treatment time www.indiandentalacademy.com

Slide 138: 

Study of temporomandibular joint laminagraphs indicate that chincup-treated subjects show significant forward bending of condyle, deepened-widened glenoid fossa, and decreased space between the condyle and fossa in comparison with those of non-chincup subjects. Another study concluded that chin-cup therapy may improve not only Class III jaw relationship but also change TMJ morphologic characteristics. www.indiandentalacademy.com

Slide 139: 

It was found that a force direction to the condyle induced a higher compressive strain at the medial surface of the condylar head and tensile strain on the distal surface, and also supported a possibility of decreased angle of the mandible. www.indiandentalacademy.com

Slide 140: 

Arat,. Akcam, and H. Gokalp studied long term effects of chin cup therapy on a treatment group of 32 patients with skeletal Class III malocclusion treated with chincup therapy. The mean age of this group was 18.4 years (range, 13.9 to 22.5 years). The mean postretention follow-up period was 5.6 years (range, 2 to 11 years), and the average treatment time was 1.8 years. The findings were compared with 2 control groups—an untreated skeletal Class III control group comprising 39 subjects (20 male, 19 female), mean age 15.5 years (range, 12.5 to 31.1 years), and a normal occlusion control group consisting of 53 subjects. www.indiandentalacademy.com

Slide 141: 

A functional examination was conducted on all subjects. Those with at least 1 sign or symptom (clicking, pain, or deviation) were identified as the “symptomatic” subgroup. The results of the study showed that chincup therapy is neither a risk factor for nor a prevention of TMD. www.indiandentalacademy.com

Slide 142: 

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